This invention relates to substantially single phase silicone copolycarbonates suitable for use in optical articles, methods for making such silicone copolycarbonates and methods for controlling the physical properties of silicone copolycarbonates. Material properties of silicone copolycarbonates are found to be controlled both by composition and method of preparation. Control of product properties by method of preparation is provided by two methods which provide identically constituted materials having different physical properties. This invention further relates to optical articles, and methods for making optical articles from the silicone copolycarbonates.
The past two decades have seen tremendous growth in the use of optical plastics in information storage and retrieval technology. Polycarbonates and other polymer materials are utilized widely in optical data storage media, such as compact disks. In optical data storage applications, it is desirable that the plastic material chosen have excellent performance characteristics such as high transparency, low water affinity, good molding characteristics, substantial heat resistance and low birefringence. Low water affinity is particularly desirable in optical data storage media applications in which disk flatness is affected by water absorption. In xe2x80x9cread throughxe2x80x9d applications successful employment of a particular optical plastic requires that it be readily molded into disks embossed with a series of very fine grooves and pits which govern critical aspects of data storage and retrieval. Replication of these grooves and pits during molding must occur with high precision and a high level of disk to disk uniformity must be achieved. Moreover the material itself must not stick to or foul the mold surfaces. Water affinity, molding characteristics, thermal and optical properties are properties of the material itself and will ultimately depend upon the structure of the optical polymer. Efforts to maximize desirable properties and repress undesirable properties in optical polymers have been intense. The chief means of discovery in this area has been through chemical synthesis and testing of new materials. Many different polymer types and structures have been prepared and evaluated. However, because each new application may require a different balance of material characteristics not currently provided by known materials, efforts directed to the discovery of new polymers has continued.
Silicone copolycarbonates as a class exhibit poor miscibility of the silicone and polycarbonate repeat units and a marked tendency toward segregation into predominantly silicone-containing and polycarbonate containing phases. This behavior limits the utility of silicone copolycarbonates. There exists a need for silicone copolycarbonate compositions which are, as defined herein, substantially single phase, which have excellent processability and low water affinity, and are suitable for use in high density optical recording media.
The present invention provides substantially single phase silicone copolycarbonates suitable for use in optical data storage applications. These and further embodiments of the invention will be more readily appreciated when considering the following disclosure and appended claims.
In one aspect, the invention relates to a substantially single phase silicone copolycarbonate comprising:
a. a repeat unit having structure I 
xe2x80x83wherein R1 and R2 are each independently at each occurrence halogen, C1-C6 alkyl or aryl,
m and n are each independently integers from 0-4,
W is a linking moiety selected from the group consisting of: a bond, a C2-C18 alkylidene group, a C3-C12 cycloalkylidene group, a carbon atom optionally substituted by one or two hydrogen atoms or one or two C6-C10 aryl groups or one or two C1-C18 alkyl groups; an oxygen atom, a sulfur atom, a sulfonyl (SO2) group and a carbonyl (CO) group; and
b. repeat units having structure II 
xe2x80x83wherein R3 is a C2-C10 alkylene group optionally substituted by one or more C1-C10 alkyl or one or more aryl groups; an oxygen atom or an oxyalkyleneoxy moiety such as:
xe2x80x94Oxe2x80x94(CH2)txe2x80x94Oxe2x80x94
xe2x80x83or an oxyalkylene moiety such as:
xe2x80x94)xe2x80x94(CH2)txe2x80x94xe2x80x83xe2x80x83
xe2x80x83where t is an integer from 2-20;
and where R4 and R5 are each independently at each occurrence C1-C6 alkoxy, C1-C6 alkyl or aryl;
z and q are independently integers from 0-4; and further
R6, R7, R8 and R9 are each independently at each occurrence C1-C6 alkyl, aryl, C2-C6 alkenyl, cyano, trifluoropropyl or styrenyl;
and p is an integer from 0-20.
This invention further relates to methods of making these silicone copolycarbonates and methods for controlling physical properties of identically constituted silicone copolycarbonates by choice of preparation method. Two methods of preparation are disclosed. In Method 1 interfacial polymerization of the starting monomers with phosgene affords a product having a blocky structure and higher glass transition temperature than an identically constituted product produced by Method 2. In Method 2, reaction of an oligomeric, non-silicone-containing bischloroformate with a silicone-containing bisphenol affords a product with a random structure and glass transition temperature lower than an identically constituted product produced by Method 1. Still further, this invention relates to optical articles made from the silicone copolycarbonates and methods of making said optical articles.
The present invention may be understood more readily by reference to the following description of preferred embodiments of the invention and the Examples included herein.
It is to be understood that this invention is not limited to specific synthetic methods or to particular compositions falling within the class of substantially single phase silicone copolycarbonates. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings.
The singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d include plural referents unless the context clearly dictates otherwise.
xe2x80x9cOptionalxe2x80x9d or xe2x80x9coptionallyxe2x80x9d means that the subsequently described event or circumstance may or may not occur, and that description includes instances where the event or circumstance occurs and instances where it does not.
xe2x80x9cBPAxe2x80x9d is herein defined as bisphenol A or 2,2-bis(4-hydroxyphenyl)propane. xe2x80x9cBCCxe2x80x9d is herein defined as 1,1-bis(4-hydroxy-3-methylphenyl) cyclohexane.
xe2x80x9cBPIxe2x80x9d is herein defined as 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
xe2x80x9cBPZxe2x80x9d is herein defined as 1,1-bis-(4-hydroxyphenyl)cyclohexane
xe2x80x9cCgxe2x80x9d is the stress optical coefficient of a polymeric material in the glassy state, measured in Brewsters (10xe2x88x9213 cm2/dyne)
xe2x80x9cCpxe2x80x9d represents the heat capacity of a material.
xe2x80x9cDegree of oligomerizationxe2x80x9d as used herein refers to the value of r in structural formula IV.
xe2x80x9cIdentically constitutedxe2x80x9d as used herein refers to silicone copolycarbonates which have roughly the same molecular weight and which contain the same relative number of moles of repeat units I and II, said relative number of moles of repeat units I and II being determined by nuclear magnetic resonance spectroscopy (NMR). Two silicone copolycarbonates are defined herein as having roughly the same molecular weight when each exhibits an Mw value which is within 10% of the Mw value measured for the other composition by gel permeation chromatography (gpc) using polystyrene standards.
xe2x80x9cMTBACxe2x80x9d is herein defined as methyltributyl ammonium chloride.
xe2x80x9cOptical data storage mediaxe2x80x9d or an xe2x80x9coptical data storage mediumxe2x80x9d refers to an article which may be encoded with data and which is read by optical means.
xe2x80x9cOptical articlesxe2x80x9d as used herein include optical disks and optical data storage media, for example a rewritable or read only compact disk (CD), a digital versatile disk, also known as DVD, random access memory disks (RAM), magneto optical (MO) disks and the like; optical lenses, such as contact lenses, lenses for glasses, lenses for telescopes, and prisms; optical fibers; information recording media; information transferring media; high density data storage media, disks for video cameras, disks for still cameras and the like; as well as the substrate onto which optical recording material is applied. In addition to use as a material to prepare optical articles, the substantially single phase silicone copolycarbonate may be used as a raw material for films or sheets.
xe2x80x9cOptical polymer xe2x80x9d refers to a polymeric material having physical characteristics compatible with use in optical data storage devices wherein light is passed through the polymeric material as part of a data reading or writing operation such as in read through optical data storage devices. The term xe2x80x9coptical polymerxe2x80x9d is used interchangeably with the term xe2x80x9coptical plasticxe2x80x9d.
xe2x80x9cSilicone copolycarbonatexe2x80x9d refers to a copolycarbonate containing both carbonate and silicone structural units. It is used herein to describe both the substantially single phase silicone copolycarbonates of the present invention as well as copolycarbonates containing silicone structural units which fall outside of the scope of the present invention.
xe2x80x9cSubstantially single phase silicone copolycarbonatexe2x80x9d is defined as a silicone copolycarbonate prepared from both silicone-containing bisphenols of formula V and non-silicone-containing bisphenols of formula III the copolycarbonate having a Tg which follows the mixing rule:
1/Tg=w1(1/Tg1)+w2(1/Tg2)
where w1 and w2 are the weight fractions of silicone containing and non-silicone containing bisphenols employed and Tg1 and Tg2 are the glass transition temperatures of the homopolycarbonates derived from the silicone-containing and non-silicone-containing bisphenols respectively.
xe2x80x9cStyrenylxe2x80x9d is defined as a 2-phenyleth-1-yl or a 1-phenyleth-1-yl group.
xe2x80x9cTrifluoropropylxe2x80x9d is defined as the 3,3,3-trifluoroprop-1-yl group.
Unless otherwise stated, xe2x80x9cmole percentxe2x80x9d in reference to the composition of a silicone copolycarbonate or polycarbonate in this specification is based upon 100 mole percent of the repeating units of the silicone copolycarbonate or polycarbonate. For instance, xe2x80x9ca silicone copolycarbonate comprising 90 mole percent of BPAxe2x80x9d refers to a silicone copolycarbonate in which 90 mole percent of the repeating units are residues derived from BPA or its corresponding derivative(s). Corresponding derivatives include but are not limited to, the polycarbonate oligomers of BPA terminated by chloroformate groups, referred to here as xe2x80x9coligomeric bischloroformatexe2x80x9d and xe2x80x9coligomeric bischloroformatesxe2x80x9d.
The terms xe2x80x9cmole percentxe2x80x9d, xe2x80x9cmole %xe2x80x9d and xe2x80x9cmol %xe2x80x9d are used interchangeably throughout this application and have the meaning given above for xe2x80x9cmole percentxe2x80x9d.
xe2x80x9cWt % Sixe2x80x9d (Weight percent siloxane) denotes the weight of [R8R9 SiO] units in a given silicone copolycarbonate polymer relative to the total weight of the silicone copolycarbonate polymer. It is obtained by multiplying the weight in grams of the silicone containing bisphenol used times the weight fraction of [R8R9 SiO] units in the bisphenol and dividing the product by the total weight in grams of all of the bisphenol monomers used in the preparation of the silicone copolycarbonate.
The terms xe2x80x9cresiduesxe2x80x9d and xe2x80x9cstructural unitsxe2x80x9d, used in reference to the constituents of the silicone copolycarbonate, are synonymous throughout the specification.
Silicone copolycarbonates as a class are prized for their improved ductility, flow and mold release behavior relative to polycarbonates which do not contain silicone. However, it is observed that silicone copolycarbonates typically phase segregate into silicone and polycarbonate phases. In many applications separation of a copolymer into separate phases presents a critical limitation upon its utility. The use of silicone copolycarbonates in read through optical data storage devices is limited by the tendency of these materials to phase separate. Phase separation negatively affects the percentage of light transmitted by the material (% light transmission) during disk reading and writing which correspondingly limits utility. Silicone copolycarbonates which were not phase separated would be useful as substrates for optical data storage devices since they would possess the excellent ductility, flow and molding properties of known phase separated silicone copolycarbonates but might additionally possess excellent light transmission, birefringence and water absorption behaviors.
Phase separation is detected by various means including percent light transmission measurements, scanning electron microscopy and glass transition temperature (Tg) behavior. Glass transition temperature is a convenient means to monitor phase behavior in silicone copolycarbonates. Known silicone copolycarbonates exhibit two glass transition temperatures, because they possess separate silicone and polycarbonate phases. This is particularly so in the case of silicone copolycarbonates possessing polydimethylsiloxane and bisphenol A polycarbonate repeat units. Such a silicone copolycarbonate behaves as though it were an immiscible blend of polycarbonate and polydimethylsiloxane polymers. Distinct Tg""s characteristic of the polycarbonate and silicone homopolymers are observed. A consequence of this behavior is that for known silicone copolycarbonates the Tg of the polycarbonate phase is essentially unaffected by the relative amount of the silicone-containing component employed.
The tendency of a silicone copolycarbonate to behave as though it were an immiscible blend of a silicone polymer and polycarbonate represents an important limitation on its utility. The present invention overcomes this limitation by providing substantially single phase silicone copolycarbonates. It has been discovered that by carefully controlling the structure of the silicone-containing bisphenol corresponding to repeat unit II silicone copolycarbonates are obtained which unexpectedly behave as though they were substantially single phase materials. The Tg""s of the substantially single phase silicone copolycarbonates of this invention are found to be intermediate between the glass transition temperatures of the corresponding homopolycarbonates of the silicone-containing bisphenol and non-silicone-containing bisphenol, Tg1 and Tg2 respectively. Moreover, the Tg""s of the silicone copolycarbonates of the present invention are consistent with the following expression (mixing rule):
xe2x80x831/Tg=w1(1/Tg1)+w2(1/Tg2)
where w1 and w2 are the weight fractions of silicone containing and non-silicone containing bisphenol respectively and Tg1 and Tg2 are defined as above. Thus the substantially single phase silicone copolycarbonates of the present invention exhibit a glass transition temperature which is dependent upon the weight fractions of the component silicone-containing and non-silicone containing bisphenols. In some instances the Tg mixing rule described above may become nonlinear and curvature at high values of w1 or w2 can be detected. In such cases the mixing rule need not accurately predict the observed Tg but rather need only predict the direction of the Tg change brought about by changing the weight fractions of the silicone-containing and non-silicone-containing bisphenols employed.
In one of its embodiments the present invention provides a substantially single phase silicone copolycarbonate exhibiting a Tg which is not only dependent upon composition, the relative amounts of residues I and II, but is also dependent upon the method of polymer preparation employed. The method of preparation may sometimes mask the effect of varying the relative amounts of the component monomers upon the Tg of the product silicone copolycarbonate. As such, the mixing rule described above has predictive value within a series of compositions in which the relative amounts of repeat units I and II vary when the materials are prepared by the same chemical process. This aspect of the present invention is further illustrated in the sections which follow.
When the substantially single phase silicone copolycarbonate containing repeat units I and II is prepared from a silicone containing bisphenol such as eugenol siloxane bisphenol and a non-silicone containing bisphenol such as BPA, it has been found that the value of p in structure II, the number of [Me2SiO] units present, must be in the range from about 0 to about 20. Otherwise, a phase segregated silicone copolycarbonate is obtained, regardless of the method of polymer preparation employed.
In a further embodiment the present invention provides a substantially single phase silicone copolycarbonate composition having increased utility in the preparation of molded optical articles relative to known silicone copolycarbonates in which the silicone and polycarbonate components phase segregate and the material behaves like an immiscible blend of a silicone polymer and a polycarbonate wherein the Tg of the polycarbonate phase is largely unaffected by the presence of, or amount of, the silicone containing phase. Thus, unlike known phase segregated silicone copolycarbonates, the compositions of the present invention are susceptible to the adjustment of glass transition temperature and those processing characteristics dependent upon glass transition temperature by varying the amount of the silicone comonomer employed in their preparation.
The present invention also provides an additional tool which augments compositional control of physical properties of substantially single phase silicone copolycarbonates. Thus, the inventors have discovered that the physical properties of certain substantially single phase silicone copolycarbonates of the invention are dependent not only upon the structure and amount of the monomers employed but also upon the method of polymer synthesis employed. The inventors have discovered, for example, that the glass transition temperature and other physical properties of two substantially single phase silicone copolycarbonates prepared using identical amounts of eugenol siloxane bisphenol and BPA may vary depending on whether the copolycarbonate was prepared by reaction of the mixture of these two monomers with phosgene directly or whether the copolycarbonate was prepared by reaction of eugenol siloxane bisphenol with an oligomeric bischloroformate prepared from the BPA (See, for example, Table 4, Examples 34-37).
In some instances it has been found that when a mixture comprising the bisphenol monomers III and V is combined with a solvent and reacted with phosgene in the presence of water, an acid acceptor and optionally a phase transfer catalyst (i.e. interfacial conditions), the rates of reaction of the bisphenol monomers III and V with phosgene or a chloroformate end group on a growing polymer chain are different enough to give compositions which are blocky. The degree to which a polymer has a blocky, or in the alternative, a random structure is determined by NMR. For the purposes of the present invention a blocky silicone copolycarbonate is defined as one in which the average block length of repeat unit II is greater than about 2. Bisphenols bearing substituents ortho to the OH group, such as eugenol siloxane bisphenol, are typically less reactive than unsubstituted bisphenols such as BPA. Phosgenation of a mixture of eugenol siloxane bisphenol having pxe2x89xa620 and BPA gives a blocky, substantially single phase silicone copolycarbonate.
The blocky substantially single phase silicone copolycarbonates comprising repeat units having structure I and repeat units having structure II are prepared by reaction of a mixture of bisphenols III and V and from about 0 to about 7 mole percent monophenol VI, based on total moles of III and V, with phosgene in the presence of an organic solvent, water, an acid acceptor and optionally a phase transfer catalyst. Thus, a mixture of bisphenols III and V together with monophenol VI is combined with an organic solvent and water and optionally a phase transfer catalyst. Sufficient aqueous alkali metal hydroxide or alkaline earth metal hydroxide is added to bring the pH of the reaction mixture to a pH value in the range between about 9 and about 12 with a pH of about 10.5 being preferred. Phosgene is then introduced into the reaction mixture together with sufficient hydroxide to maintain a pH of about 10.5. When the desired amount of phosgene has been introduced, usually an amount in the range of between about 100 mole % and about 200 mole % based on total moles of bisphenols III and V employed, the reactor is purged of any excess phosgene and the product substantially single phase silicone copolycarbonate having a blocky structure is isolated.
Suitable organic solvents which can be used are, for example, chlorinated aliphatic hydrocarbons, such as methylene chloride, carbon tetrachloride, dichloroethane, trichloroethane and tetrachloroethane; substituted aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene, and the various chlorotoluenes. The chlorinated aliphatic hydrocarbons, especially methylene chloride, are preferred.
Alkali metal or alkaline earth metal hydroxides which can be employed are, for example, sodium hydroxide, potassium hydroxide, and calcium hydroxide. Sodium and potassium hydroxides, and particularly sodium hydroxide are preferred.
Suitable phase transfer catalysts (PTC) are illustrated by but are not limited to the following: Et3N, [CH3(CH2)3]4NZ, [CH3(CH2)3]4PZ, [CH3(CH2)5]4NZ, [CH3(CH2)6]4NZ, [CH3(CH2)4]4NZ CH3[CH3(CH2)2]3NZ, and CH3[CH3(CH2)3]3NZ, where Z is selected from Cl or Br.
Alternatively bisphenol component III is first oligomerized in the presence of excess phosgene to a give an oligomeric bischloroformate IV wherein r has a value in a range between about 1 and about 20 and preferably in a range a range between about 5 and about 10. The bischloroformate IV is then reacted with the silicone containing bisphenol V in a solvent in the presence of water, an acid acceptor and optionally a phase transfer catalyst to give a silicone copolycarbonate having a random structure. A silicone copolycarbonate having a random structure is defined herein as one in which the average block length of repeat unit II is about 1. In order to achieve incorporation of all of the components and an average block length of repeat unit II of about 1 there must be a preponderance of chloroformate groups of bischolorformate oligomer IV relative to the number of OH groups of silicone-containing bisphenol V. In some instances, as when a very small amount of the silicone-containing bisphenol is employed, for example less than 1 mole percent relative to the number of moles of repeat units I present in the oligomeric bischloroformate IV, the number of chloroformate end groups remaining after the reaction of bischloroformate IV with bisphenol V and monophenol VI may be substantial and the molecular weight of the product insufficient to afford the properties desired. Chloroformate end groups may be hydrolyzed by base to afford phenolic end groups which react further with remaining chloroformate end groups to build molecular weight of the product silicone copolycarbonate. For these reasons the average block length of repeat unit I in substantially single phase silicone copolycarbonates having a random structure prepared by reaction of an oligomeric bischloroformate IV with a silicone-containing bisphenol V and a monophenol VI is always at least the value of r.
In structures III and IV R1 and R2 each represent independently at each occurrence halogen, C1-C6 alkyl or aryl groups; m and n are independently integers from 0-4; and r is an integer from 1-20. W is a linking moiety selected from the group consisting of: a bond, a C2-C18alkylidene group, a C3-C12 cycloalkylidene group, a carbon atom optionally substituted by one or two hydrogen atoms or C6-C10 aryl groups or C1-C18 alkyl groups; 
an oxygen atom, a sulfur atom, a sulfonyl (SO2) group and a carbonyl (CO) group. 
Thus, a bisphenol III is mixed with an organic solvent and optionally a phase transfer catalyst. Sufficient aqueous alkali metal hydroxide or alkaline earth hydroxide is added to raise the pH of the bisphenol reaction mixture prior to phosgenation, to a value of about 10.5. This can result in the dissolution of some of the bisphenol into the aqueous phase. Aqueous alkali, or alkaline earth metal hydroxide is used to maintain the pH of the phosgenation mixture near the desired pH for the reaction, which is in a range of between about 8 and about 10.5. The pH can be regulated by recirculating the reaction mixture past a pH electrode which regulates the rate of addition of the aqueous alkali metal or alkaline earth metal hydroxide.
When the bisphenol III has been converted to the oligomeric bischloroformate IV the silicone containing bisphenol V and monophenol VI may be introduced 
wherein R3 is a C2-C10 alkylene group optionally substituted by one or more C1-C10 alkyl or aryl groups, an oxygen atom or an oxyalkyleneoxy moiety such as
xe2x80x94)xe2x80x94(CH2)txe2x80x94Oxe2x80x94
or an oxyalkylene moiety such as
xe2x80x94)xe2x80x94(CH2)txe2x80x94
where t is an integer from 2-20;
R4 and R5 are each independently at each occurrence C1-C6 alkoxy, C1-C6 alkyl or aryl;
z and q are independently integers from 0-4;
R6, R7, R8 and R9 are each independently at each occurrence C1-C6 alkyl, aryl, C2-C6 alkenyl, cyano, trifluoropropyl, styrenyl;
p is an integer from 0-20;
R10 is a C1-C20 alkyl group optionally substituted by one or more C6-C10 aryl groups; a C1-C20 alkoxy group optionally substituted by one or more C6-C10 aryl groups; and
s is an integer from 0-5.
The pH of the mixture then may be raised to between about 10 and about 12 and additional phase transfer catalyst added. Reaction of bischloroformate IV with a silicone containing bisphenol having structure V and a monofunctional phenol VI in the presence of a solvent, water, an acid acceptor and optionally a phase transfer catalyst affords a silicone containing copolycarbonate incorporating repeat units I and II and terminal groups derived from VI having a random structure. Suitable solvents, alkali metal hydroxides and phase transfer catalysts are those described herein as being useful in the preparation of substantially single phase silicone copolycarbonates having a blocky structure.
After reaction between the silicone containing bisphenol V, monophenol VI and the oligomeric bischloroformate IV is complete the reaction mixture may be checked for the presence of unreacted chloroformate end groups. These may be eliminated by the introduction of a small amount of a tertiary amine, such as triethylamine, or additional bisphenol III or V or additional monophenol VI.
In one embodiment the present invention provides substantially single phase silicone copolycarbonates in which repeat unit I is preferably 
represented by structure VII wherein W is defined as in formula I; and repeat unit II is preferably represented by formula VIII wherein R3, R4, R5 and p are defined as in formula II. In addition, it has been found that it is particularly 
preferred that repeat unit I be represented by structure IX and that repeat unit II be represented by formula X. 
In another embodiment the present invention provides substantially single phase silicone copolycarbonates in which it is preferred that repeat unit I be represented by structure XI and that repeat unit II be represented by formula X. 
Representative units of bisphenol III used in the preparation of both blocky and random substantially single phase silicone copolycarbonates include, but are not limited to residues of 2,2-bis(4-hydroxyphenyl)propane (BPA); 2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl)pentane; 2,2-bis(4-hydroxy-3-methylphenyl)propane; 2,2-bis(3-ethyl-4-hydroxyphenyl)propane; 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane; 1,1-bis(4-hydroxy-3-methylphenyl)cyclopentane; 1,1-bis(4-hydroxy-3-methylphenyl)cycloheptane. Residues of BPA are preferred as bisphenol III.
Representative examples of siloxane-containing bisphenols V include, but are not limited to eugenol siloxane bisphenol and other siloxane containing bisphenols shown below in which p is an integer from 0 to 20. 
The representative siloxane bisphenols 4-allyl-2-methylphenol siloxane bisphenol, 4-allylphenol siloxane bisphenol, 2-allylphenol siloxane bisphenol, 4-allyloxyphenol siloxane bisphenol and 4-vinylphenol siloxane bisphenol are named after the aliphatically unsaturated phenols from which they are prepared. Thus, the name eugenol siloxane bisphenol denotes a siloxane bisphenol prepared from eugenol (4-allyl-2-methoxyphenol). Similarly the name 4-allyl-2-methylphenol siloxane bisphenol indicates the siloxane bisphenol prepared from 4-allyl-2-methylphenol. The other names given follow the same naming pattern.
Siloxane bisphenols are prepared by hydrosilylation of an aliphatically unsaturated phenol with a siloxane dihydride in the presence of a platinum catalyst. This process is illustrated below for eugenol siloxane bisphenol. 
In one of its embodiments the present invention is directed to the use of siloxane dihydrides having up to 20 [Me2OSi] repeat units in the preparation of siloxane containing bisphenols. Siloxane dihydrides having up to 20 repeat units may be prepared by equilibration of tetramethyldisiloxane with a cyclic siloxane such as octamethylcyclotetrasiloxane in the presence of an acid catalyst. Reaction of the siloxane dihydride with an aliphatically unsaturated phenol in the presence of a platinum catalyst affords the siloxane-containing bisphenol.
Alternatively, an aliphatically unsaturated phenol may be reacted with tetramethyldisiloxane in the presence of a platinum catalyst to give a siloxane bisphenol V in which p has a value of 1. Equilibration of said siloxane bisphenol with a source of [Me2SiO] units such as octamethylcyclotetrasiloxane in the presence of an acid catalyst then affords a siloxane bisphenol V having a value of p greater than 1.
Aliphatically unsaturated phenols are illustrated by but not limited to 4-allyl-2-methoxyphenol (eugenol), 2-allylphenol, 4-allyl-2-methylphenol, 4-allylphenol, 4-allyloxyphenol and 4-vinylphenol.
Monophenols VI are typically added as a means of controlling the molecular weight of the siloxane copolycarbonate and the identity of the polymer end groups. Typically the amount of monophenol VI employed is in a range from about 0 mole percent to about 7 mole percent based on the total moles of repeat units I and II. Suitable monophenols are exemplified by, but not limited to, the following: phenol; 4-t-butylphenol; 4-cumylphenol; 3,5-dimethylphenol and 2,4-dimethylphenol.
The substantially single phase silicone copolycarbonates of the present invention may comprise repeat units I in a range between about 60 mole % and about 99.9 mole % and repeat units II in a range between about 0.1 mole % and about 40 mole %. Generally it is preferred that the silicone copolycarbonates of the present invention comprise repeat units I in a range between about 80 mole % and about 99.9 mole % and repeat units II in a range between about 20 mole % and about 0.1 mole %. Substantially single phase silicone copolycarbonates comprising repeat units I in a range between about 90 mole % and about 99.5 mole % and repeat units II in a range between about 0.5 mole % and about 10 mole % are especially preferred.
In one of its embodiments the present invention provides substantially single phase silicone copolycarbonates in which the value of the integer p in repeat unit II is more preferably less than about 5. In such cases it has been discovered that repeat units I and II show enhanced compatibility with one another in copolymers containing them and such copolymers are especially resistant to phase segregation. However, when the value of p is in the range between about 10 and about 20 the use of more than about 20 mole % of the silicone containing comonomer V may result in compositions in which the silicone and polycarbonate phases tend to segregate. Thus, it has been discovered that when preparing the compositions of the present invention where the value of p is in the range from about 10 to about 20 the silicone containing bisphenol V be limited to no more than about 20 mole % of the total amount of bisphenol employed and preferably no more than about 10 mole %.
In one of its embodiments the present invention provides substantially single phase silicone copolycarbonates in which the value of the integer p in repeat unit II is more preferably about 2 or less. In such cases it has been discovered that the stress optical coefficient, Cg, is substantially reduced relative to BPA polycarbonate by an amount greater than would be predicted by a simple dilution model whereby the relatively highly birefringent BPA polycarbonate is diluted with a non-birefringent diluant. This effect is illustrated in Table 5 of the examples for substantially single phase silicone copolycarbonates containing repeat units based upon BPA and eugenol siloxane bisphenol respectively.
The substantially single phase silicone copolycarbonates of the present invention may optionally be blended with other polymers such as polycarbonates, copolycarbonates, copolyestercarbonates and polyesters which are illustrated by but not limited to the following: bisphenol A polycarbonate, BCC polycarbonate, BPZ polycarbonate, copolycarbonates of BPA and BPI, BPA-dodecanedioic acid copolyestercarbonate, and polyethylene terephthalate.
The substantially single phase silicone copolycarbonates of the present invention may optionally be blended with any conventional additives used in various applications such as the preparation of optical articles. Said conventional additives include but are not limited to UV absorbers, antioxidants, heat stabilizers, anti static agents and mold release agents, slip agents, antiblocking agents, lubricants, anticlouding agents, coloring agents, natural oils, synthetic oils, waxes, organic fillers and mixtures thereof.
In particular, it is preferable to form a blend of the substantially single phase silicone copolycarbonate and additives which aid in processing the blend to form the desired molded article such as an optical article. The blend may optionally comprise from about 0.0001 to about 10% by weight of the desired additives, more preferably from about 0.0001 to about 1.0% by weight of the desired additives.
Examples of the aforementioned heat stabilizers, include, but are not limited to, phenol stabilizers, organic thioether stabilizers, organic phosphite stabilizers, hindered amine stabilizers, epoxy stabilizers and mixtures thereof. The heat stabilizer may be added in the form of a solid or liquid.
Examples of UV absorbers include, but are not limited to, salicylic acid UV absorbers, benzophenone UV absorbers, benzotriazole UV absorbers, cyanoacrylate UV absorbers and mixtures thereof.
Examples of the mold release agents include, but are not limited to natural and synthetic paraffins, polyethylene waxes, fluorocarbons, and other hydrocarbon mold release agents; stearic acid, hydroxystearic acid, and other higher fatty acids, hydroxy fatty acids, and other fatty acid mold release agents; stearic acid amide, ethylenebisstearamide, and other fatty acid amides, alkylenebisfatty acid amides, and other fatty acid amide mold release agents; stearyl alcohol, cetyl alcohol, and other aliphatic alcohols, polyhydric alcohols, polyglycols, polyglycerols and other alcoholic mold release agents; butyl stearate, pentaerythritol tetrastearate, and other lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, polyglycol esters of fatty acids, and other fatty acid ester mold release agents; silicone oil and other silicone mold release agents, and mixtures of any of the aforementioned.
The coloring agent may be either pigments or dyes. Organic coloring agents may be used separately or in combination in the invention.
The desired optical article may be obtained by molding the substantially single phase copolycarbonate or alternatively molding a blend of the substantially single phase copolycarbonate with a polycarbonate, a copolycarbonate, a copolyestercarbonate or a polyester by injection molding, compression molding, extrusion methods and solution casting methods. Injection molding is the more preferred method of forming the article.